I have to wonder if this was UK payback for Trump favoring Brexit and Obama opposing Brexit?
It's much deeper than that.
There is an unspoken understanding among the ruling classes of Europe, the UK, Australia, NZ, Canada, and of course the US that a world governing structure made up of a "global economy", "international law", and "transnational institutions" is both necessary and desirable, and that furthermore the US should and will provide expeditionary forces to bring minor objectors into line, such as Saddam and Gadaffi, with reserve nuclear forces to threaten and contain potential outsiders such as Russia.
If the price is more US debt to the international banks and a few thousand dead deplorables every ten years or so, so what?
Brennan and his counterparts share a perfect understanding, with the rubric, "think of it aways, speak of it never". Eight years of "Obama" was more than they could ask for.
Trump was a true nightmare, a nationalist zombie rising from the grave, someone who not only was not on board but who had enough brains and enough international business experience to have at least a vague understanding (much better now, I'm sure) of what was afoot. As soon as they realized it wasn't a joke, they swung into action to stop him, and I don't believe that they are finished, not by any means.
The movie "They Live" illustrated the shock the globalists must have felt when Trump started his string of victories: